To better predict the high-frequency switching operation of the half-bridge circuit in power converters, the value of the parasitic elements of these devices must be accurately evaluated. A new MOSFET-based half-bridge circuit parasitic inductances extraction method using two-port S-parameters is proposed in this paper. By changing the terminal connection of the half-bridge circuit, we can treat it as several different two-port networks, and then detailed network analysis can be performed on it. The parasitic parameters of multi-terminal actual circuits such as half-bridge can be extracted accurately and quickly through the simple measurement steps and calculations of the proposed method.